A honeycomb structure is broadly used as a filter for collecting dust from an exhaust gas, for example, a diesel particulate filter (DPF) for collecting and removing a particulate material (particulates) such as soot included in an exhaust gas from a diesel engine or the like.
The honeycomb structure used for such a purpose has a problem that the structure is exposed to the immediate temperature change of the exhaust gas or local heat generation, a non-uniform temperature distribution is easily generated in the structure, and cracks are generated owing to the distribution. To solve such a problem, a method is suggested in which the honeycomb structure is constituted of a plurality of honeycomb segments, and the honeycomb segments are integrally joined by a joint material made of an elastic material, whereby a thermal stress exerted to the honeycomb structure is alleviated (e.g., see Patent Document 1).
In general, the temperature distribution of the honeycomb structure used in the DPF becomes the most non-uniform state during the regeneration of the filter, that is, during the performing of a treatment for heating the honeycomb structure and burning and removing the soot to return, to an initial state, a pressure loss raised by the soot deposited in the honeycomb structure with an elapse of time. However, during this regeneration, the thermal stress cannot sufficiently be alleviated even in the honeycomb structure employing the above constitution, whereby not a few cracks (especially annular cracks in the diametric direction of the honeycomb structure) are generated, and the generated cracks are further developed. Patent Document 1: JP-A-2000-279729